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well all.

i currently have 1.3mm skimmed off my head which i think gives me around 10.3:1 compression ratio. Torque down low has very noticably increased.

I was wondering what compression you all think the standard bottom end will take. I know i cant skim more than about 1.6mm or else it will start cuting into the bowl area.

just curious as i was thinking about building another head.

thanks

I would worry about your piston to valve clearance ,and the fact that your valve seats are closer to the head.Besides that i think stock pistons can handle a lot of compression.You see a lot of guys running 12 :1 compression on p29 pistons and such.It just all depends on what condition your piston rings and pistons are.

If you want more compression then 10,3 :1 you would be better of getting high compression pistons.Milling your head to 1.6mm gives you 10,7 :1 compression which isn't really worth the trouble.

Btw the bowl area is inside the intake/exhaust ports.And the D14a4 's quench area is about 2.5mm deep .

sorry i forgot what it was called

yea thats y i can only skim around 1.6mm off the head because of the piston to valve clearance. dont think i could go anymore or else i wuld start to run into trouble.

high compression pistons could be an idea altho i dnt fancy spending too much money on them.

cheers for the reply!

Can i ask you guys, what is a good value for skim a D16Y8 head with stock pistons? remember, D16Y8 head is lot more "closed", with smaller chambers. cheers

Law_ wrote:Can i ask you guys, what is a good value for skim a D16Y8 head with stock pistons? remember, D16Y8 head is lot more "closed", with smaller chambers. cheers

D16y8 head has the quench pads closed up which gives you a bigger quench area which is better in high compression ratio like 12 :1.Less prone to pre detonation.
If you mill the head 0.025" or 0.64mm you'll get a compression ratio of 10:1 on a D14a4/a3 bottem end. 0.025" milled is not too much imo.

Seems nice. will mill that 0.64mm and remove a layer from head gasket then ! Should be fine Thanks !

I was just wondering if anyone knows what the comp ratio is of a d14 wit pm2 piston's (at least I think that's what's in my a2) and a z6 head.

or even if anyone knows the any info on the pistons.